The overhead squat assessment promoted by NASM (Clark & Lucett, 2011) provides a useful evaluation of the functional status of the latissimus dorsi during a common movement (video example here). The OHS requires that both trunk extension and shoulder flexion occur simultaneously, either or both of which may be altered if the muscle has become chronically shortened and tight. When the lats are hypertonic, shoulder range or motion (ROM) is altered due to excessive internal rotation and depression of the humerus, which further affects the actions of the scapula. This can be seen when an individual’s arms habitually fall forward past the line of the torso during the eccentric phase of the squat in an OHS evaluation, which is an indication of the arthrokinematic (joint movement) compensations needed to accommodate functional ROM as the muscle attempts to maintain a shorter distance between origin and insertion (for an excellent visual of how this occurs, take a look here).
A dysfunction at either the shoulders (inability to maintain starting flexion) or the LPHC (excessive arching of the lumbar spine) will be apparent. The degree to which the hypertonicity is distal or proximal may be assessable by the order in which shoulder or LPHC ROM are affected. Hypertonic lats can also indicate problems with internal shoulder rotation and a relative under activity by the external humeral rotators. An athlete or student who cannot squat without his or her arms moving past the plane of the ears exhibits these symptoms, and will likely demonstrate “forward rolled” shoulders.
Although squatting and punching may seem like two unrelated actions, the ROM for either may be affected by hypertonic latissimi. The cross provides a fairly good example for examining how the lat acts as an antagonist and synergist during punching actions. The fundamental actions of the initiation of the punch are shoulder flexion, elbow extension, and scapular protraction, with the degree of flexion possible at the shoulder being a major determinant in both the trajectory and velocity of the punch. The degree of adduction and abduction required are variable, but typically, alignment of the fist with the shoulder is optimal (Dempsey, 1950). If the lats are hypertonic, optimal kinematics for the punch will be difficult to achieve, and chances of chronic glenohumeral or rotator cuff injury are increased.
The shoulder kinematics of the cross are accompanied by ipsilateral hip extension, knee flexion and plantar flexion, the subjective feeling of which has been described as “sitting down” on the punch. At this point in the kinetic chain, the lumbopelvic hip complex can be affected in the frontal and transverse planes by the status of the latissimi on either side. Shoulder ROM will also be affected via the actions of the lat upon the humerus. A combat athlete or martial artist with hypertonic lats will exhibit excessive lumbar extension and/or inward humeral rotation while punching, and will also demonstrate an inability to maintain shoulder flexion during the OHS (open martial arts seminars can be a virtual buffet of examples of this, with accompanying complaints of shoulder pain/injury). Similarly, preferential use of the trapezius to achieve shoulder elevation (to compensate for the lat’s lack of extensibility), and/or lumbar hyperextension can often be observed during performance of the punch.
Due to the shared role of the latissimus dorsi in punching and in the OHS, the OHS (Clark & Lucett, 2011) is a useful evaluation of the status, or the effects of training upon this muscle. Considering that fighting arts and sports typically involve movements that require concurrent proximal and distal actions of the lats, upper and lower body performance deficits for a variety of skills and techniques may be indicated in OHS assessments.
Clark, M. A., & Lucett, S. C. (2011). Chapter 6 Movement Assessments. NASM Essentials of Corrective Exercise Training. Philadelphia: Lippincott Williams & Wilkins.
Dempsey, J. (1950). Championship Fighting: Explosive Punching & Aggressive Defense. New York: Jack Dempsey.